Knotting mechanism

ABSTRACT

This invention relates to a knotter mechanism for a bundle tying machine, including a sliding knotter carriage having a knotter rotatably mounted thereon, a rotatably mounted cam plate, whereby rotation of the cam plate will cause sliding movement of the carriage between an operative and an inoperative position a drawslide mechanism and twine lifter arm correctly to position a length of twine and means to rotate and actuate the knotter when the carriage is in the operative position to tie a knot in the twine.

nited States Patent inventors Michael lvan Mercer Kent; Terry Arthur Fleming, Kent; Sydney Tyes, Clacton-on-Sea; Donald Sutehall, Harlow, all of, England Appl. No. 874,296 Filed Nov. 5, 1969 Patented Aug. 24, 1971 Assignee Harris lntertype Limited Slough, Enghnd KNOTTING MECHANISM 12 Claims, 9 Drawing Fig.

US. Cl 289/2 Int. Cl A0ld 59/04 Field of Search 289/2, 14, 18

[56] References Cited UNITED STATES PATENTS 3,179,453 4/1965 Walters 289/18 3,232,652 2/1966 Bonga 289/14 3,359,023 l2/l967 Aubery 289/2 Primary Examiner Louis K. Rimrodt Attorney-Baldwin, Wight, & Brown ABSTRACT: This invention relates to a knotter mechanism for a bundle tying machine, including a sliding knotter carriage having a knotter rotatably mounted thereon, a rotatably mounted cam plate, whereby rotation of the cam plate will cause sliding movement of the carriage between an operative and an inoperative position a drawslide mechanism and twine lifter arm correctly to position a length of twine and means to rotate and actuate the knotter when the carriage is in the operative position to tie a knot in the twine.

PATENTED M1824 ism SHEET 5 OF 8 PATENTED ISYI SHEET 8 [1F 8 PATENIED M1824 i971 sum 8 OF 8 KN OTTING MECHANISM This invention relates to a knotting mechanism for tying together, in a knot, two pieces of twine and, more particularly, for tying to itself a length of twine which has been looped around a bundle, such as a stack of newspapers.

According to the present invention, a knotter mechanism suitable for use in a bundle tying machine includes a frame, a knotter carriage mounted for sliding movement relative said frame between a forward operative position and a rearward inoperative position, a knotter mounted on said carriage and rotatable relative thereto, a cam plate having a cam track mounted for rotation relative said frame, a cam follower carried by said carriage and engaging said cam track, whereby rotation of said cam plate will cause said sliding movement of the carriage between its operative and inoperative positions, and means to rotate said knotter when said carriage is in its forward operative position.

Preferably, the cam follower is mounted on the end of a shaft carrying the knotter, the shaft being rotatably mounted in and passing through the carriage. Preferably also a gear segment is provided on the cam plate and a gear wheel is provided on the shaft intermediate the knotter and the cam follower, the arrangement being such that when the carriage is in its forward operative position, the gear segment is presented for engagement with the gear wheel to cause rotation of the shaft and hence the knotter.

A spring loaded detent may be mounted on the carriage and arranged normally to engage with the gear wheel, said detent being released from engagement with the gear wheel when said segment is presented thereto.

In the preferred arrangement, a draw slide cam plate is mounted in back to back relationship with the above mentioned cam plate so as to rotate with it. A draw slide control arm is connected at one end to a draw slide mechanism and is pivoted at its other end to the frame. A cam follower is pro vided intermediate the ends of the arm and is arranged to engage with a cam track on the draw slide cam plate, the shape of the cam track on the draw slide cam plate being such as to cause reciprocal movement of the draw slide upon rotation of the cam plate. The cam tracks in the two cam plates are so arranged that the draw slide will move from one side of the knotter to the other prior to the knotter reaching its forward operative position, and once the knotter has begun to rotate and has rotated through approximately 180 the draw slide will move back across the knotter to its original position.

A twine lifter arm may be provided pivotally connected to the frame and a cam may be provided on the carriage whereby, upon the carriage beginning its forward movement,

the cam engages under the twine lifter arm and lifts it to bring a length of twine into a correct position for engagement by the knotter.

The knotter comprises a fixed upper jaw and a pivoted lower jaw and a bell crank is provided for locking the jaws during movement of the carriage, the arrangement being that the free end of one of the bellcranks arms is arranged to lock the lower jaw and is releasable only when the carriage returns to its rearward position thereby causing the bellcranks other arm to contact an abutment to pivot the bellcrank and release the jaw.

The invention is now described with reference to the drawings, accompanying the provisional specification, in which;

FIG. 1 is a schematic rear elevation of one embodiment of bundle tying machine incorporating the knotting mechanism of the present invention,

FIG. 2 is a front elevation of the knotting mechanism,

FIG. 3 is a section on the line III-[II of FIG. 2,

FIG. 4 is a plan view of part of the knotting mechanism, at the beginning of a cycle, the actual knotter being omitted for clarity,

FIG. 5 is a plan view showing the parts in the same position as in FIG. 4, but with a stripper assembly removed and showing the knotter.

FIG. 6 is a further plan view showing the relationship of parts at a further stage in the cycle.

FIG. 7 is a further plan view showing the relationship of other parts at the same stage in the cycle as is shown in FIG. 6.

FIG. 8 is a further plan view at a halfway stage in the cycle, and

FIG. 9 is a scrap view showing a detail of the knotter locking mechanism.

Referring to FIG. 1, there is shown schematically a bundle tying machine of the type incorporating a chain 1 to carry a length of twine around the four sides of a bundle 2 resting on a support table 3. The twine is held by a twine retaining button 4 carried by the chain, and after being carried round the bundle, has a substantially vertical run 5 leading back to the supply (not shown), a substantially horizontal run 6 terminating in the free end of the twine which is held by the button 4, and two further runs contacting, respectively, two sides of the bundle. Before the twine is tightly secured in position around the bundle, the bundle may be compressed by a compression plate (not shown) and the twine is then secured in position by tying the end of the run of twine 6 to the run of twine 5 by means of a knotting mechanism 9, which is driven by an electric motor (not shown). It will of course be appreciated that the knotting mechanism 9 may be used with any known type of tying machine, for example with a ring tyer or a cross tyer.

Referring particularly to FIG. 2-4, the knotting mechanism is made up of a main frame 11 mounting an inverted drawer slide control cam plate 13 in back-to-back relation with a main knotter control cam plate 15, a drawer slide subframe l7 and a stripper assembly subframe 19. The main frame 11 is made up of two upright side members 20 spaced apart by a main support flange 21. The upper ends of the members 20 are formed with inwardly directed portions 23 to which the stripper subframe 19 is releasably connected, and the flange 21 is provided with a depending boss 25 having a central passage 27 formed therein and in which a drive shaft 29 is mounted by means ofsuitable bearings 31, 33. A circular plate 35 is secured to the top end of the drive shaft 29 and the shaft is driven by a pulley 37 which is driven from a belt from the motor. Suitable clutch and brake devices 39 are provided for selectively driving the shaft 29.

The drawer slide cam plate 13 and the main cam plate 15 are secured to each other and to the circular plate 35 in concentric relationship thereto by means of studs 41 and pins 43. A cam track 44 for controlling a draw slide which is generally indicated at 45 is provided in the under surface of the cam plate 13 and a main knotter control cam track 47 is formed in the upper surface of the cam plate 15.

A horizontal channel section guide track 49 is provided in each of the free edges of the inturned portions 23 of the main frame in which tracks a knotter carriage 51 slides. A knotter block subassembly 53 is supported on the knotter carriage 51 and includes a main mounting block 55, a knotter 57 mounted for rotation about a vertical axis, and a knotter clamping plate 59. The knotter 57 has an upper jaw 61 and a lower jaw 63 pivotally connected to the upper jaw, the lower jaw extending rearwardly and downwardly of the upper jaw and terminating in an arm mounting a cam follower roller 65. The upper jaw 61 is integral with a vertical mounting shaft 67 which passes through the carriage 51 and has a gear wheel 69 mounted thereon immediately below the carriage 51. The shaft 67 extends beyond the gear wheel 69 and has a cam follower roller 71 mounted on its lower end, the arrangement being such that the cam follower roller 71 engages in the cam track 47 provided in the main cam plate 15. The knotter carriage 51 slides between a rearward inoperative position which is shown in FIGS. 4 and 5 and a forward operative position which is shown in FIGS. 6, 7 and 8, rotation of the main cam plate 15 causing this sliding movement. A cam 72 having a substantially semicircular profile is also mounted on the carriage 51, for a purpose to be described hereinafter.

A gear sector 73 having a flat top with a chamfered end portion 74 is mounted on the main cam plate 15 and its gear teeth, all of which are of equal size with the exception of a leading tooth 75, which is of double size, are arranged so as to mesh with the gear teeth provided on the gear wheel 69, when the carriage 51 is in a forward position, thereby causing the knotter to rotate as will hereinafter be described. The knotter is prevented from rotating except when its gear wheel 69 is in engagement with the sector 73 by means ofa spring loaded detent 76 (see FIG. 9) which engages in the oversized root provided in the gear wheel 69 for engagement with the tooth 75. Mounted on the rear of the block 55 for pivotal movement about a horizontal pivot pin 76a is a substantially L-shaped jaw locking device or bellcrank 77 having a substantially horizontal arm 79 and a substantially vertical arm 81, the arrangement being such that the arm 79 is biased by a spring 86 so that its end face abuts the cam follower roller 65 thereby preventing opening of the lowerjaw 63, except when the slider plate is in its rearward inoperative position, as will hereinafter be described. Opening and closing of the knotter jaws 61, 63 is controlled by a cam track for the cam follower 65, the cam track being formed by ajaw opening cam surface 83 (see FIG. which is mounted on the block 55 and which also acts as a bearing and as a spacer member for the knotter 57, and by a jaw closing cam surface 84 formed on a substantially arcuate member 85.

A pair of spaced apart twine engagement arms 87 and 89 are mounted on a side edge of the block 55, the arm 87 being provided with an inclined leading face 91 and an upwardly facing recess 93 and the arm 89 being of similar shape, but inverted with respect to the arm 87, so that the two recesses are substantially in alignment with each other. A pair of stripper jaw opening cams 95 is mounted in spaced relation on the rear ofan upper portion 97 ofthe block 55.

Twine stripping mechanism is mounted about the knotter 57 on the underside of the stripper subframe 19, and comprises a pair of stripper fingers 101, 103 pivotally attached respectively to the sub frame at 105, 107. A tension coil spring 109 is attached between the fingers 101, 103 so as normally to bias their heads 111, 113, into engagement with each other. Each head 111, 113, is formed with a semicircular cut away portion 114 (FIG. 2) arranged to fit closely around the leading part of the jaws 61, 63 of the knotter 57. A pair of adjustable abutments 115 is carried by the frame 19 against which an upstanding part 116 of the fingers is arranged to bear to prevent the heads 111, 113 banging together. The stripper fingers are so located that when the knotter carriage 51 is moved to its forward operative position, the cams 95 engage the side edges of the stripper fingers (see FIG. 7), and move the heads of the stripper fingers apart when the knotter is in its operative position. An L-shaped plate 117 is mounted on the underside of the subframe 19 and extends rearwardly therefrom and an adjustable abutment member 118 extends inwardly from the depending arm of the plate 117 for engagement with the upstanding arm 81 of the jaw locking mechanism or bellcrank 77. Hence, as the carriage and hence the knotter moves rearwardly, the member 118 is struck by the arm 81 causing the member 77 to pivot and move its arm 79 out of abutting engagement with the cam follower 65.

A twine lifter arm 119 arranged to engage the cam 72 is pivotally mounted about a horizontal axis to a vertical portion of the subframe 19, and the leading edge of this arm 119 is provided with an elongated trough 121 for engaging he run of twine 6 and lifting it into the correct position for engagement by the jaws of the knotter. A knife 123 which is forwardly inclined, is rigidly attached to the leading edge of the vertical portion on the other side of the subframe 19, the frame being suitably recessed above the knife as at 125.

In a modified arrangement, the fixed knife 123 is replaced by a modified knife mounted for rocking movement about a horizontal axis on the twine engagement arm 89. The lower edge of the knife is provided with a cam surface arranged to engage one oftwo cams projecting outwardly from the vertical portion on the said other side of the subframe 9. As the knotter carriage, and hence the knife pivotally mounted on the arm 89 moves to a forward position, the knife is tilted downwardly by one of the cams, and at the end of the forward stroke of the knotter carriage, the twine engages in the recesses 93. As the knotter carriage moves to its rearward inoperative position, the knife is raised by engagement of the cam surface on its lower edge with the other cam, and as the knife and the arm of the hook 89 are adjacent to each other, the knife cuts the twine trapped in the recesses.

The draw slide 45 is provided to ensure that the length of twine 5 is correctly positioned before a knotting operation is begun. The draw slide subframe 17 comprises a substantially rectangular plate 131, a pair of spacer blocks 133 secured to the front face of the plate 131 towards each end thereof and a guide strip 135 secured, at the top, to the front face of the two blocks 133, A guide shaft 137 is rigidly secured between the two inwardly turned faces of the blocks 133 and a draw slide block 139 is mounted for sliding movement on the shaft 137. The block 139 is prevented from pivoting on the shaft 137 by the member 135 and a further guide member 141 which is releasably secured to the top edge of the plate 131 and has its guide surface just overhanging the leading face of the plate. A draw slide hook 143 is releasably secured to the top of the draw slide block 139 and this hook is arranged to engage the length of twine 5. A tension coil spring 145 is connected between the draw slide block and the block 133 so as constantly to bias the block to the right as shown in FIG. 2 and prevent any play in the control mechanism to be described. The draw slide is controlled by the draw slide cam plate 13 and a control arm 147 pivotally connected at 149 to the main frame, and which has a cam follower roller 151 intermediate the ends of the arm, which roller engages in the cam slot 44 in the cam plate 13. The other end of the arm 147 has a slot 152 formed therein and a pin 153 depending from an extension in the block 139 engages in the slot 151. Hence rotation of the cam will cause reciprocating movement of the draw slide mechanism. An arm supporting plate 154 is releasably attached to the main frame 11, and this prevents the arm 147 from falling away from the pin 153.

The mechanism operates in the following manner. Once a bundle has been presented at the tying station, the clamping device clamps the bundle and a length of twine is placed around the bundle, in known manner, and as is shown in FIG. 1. Once the twine is in this position, the knotter mechanism is automatically actuated to begin the tying cycle and at this stage, it will be in the position shown in FIGS. 3, 4 and 5. The clutch and brake means 39 will be operated in known manner to cause rotation of the shaft 29 and this will cause the two cam plates 13 and 15 which are secured together in back to back relationship, to start rotating. As the main cam plate 15 moves from the position shown in FIGS. 4 and 5 to the position shown in FIG. 6, the carriage 51 and hence the knotter will be moved forwardly towards its forward operating position since the first part of the cam track 47 is of decreasing radius. The knotter will be locked against rotation by means of the spring loaded detent 76 engaging in the double sized root between the gear teeth on the gear wheel 69. At the beginning of the cycle, the cam track 44 in the draw slide cam plate 13 is so shaped as to cause the cam follower roller 151 on the arm 147 to move to the right, thus causing the arm 147, and hence the draw slide hook 143 to move to the right from the position shown in FIG. 4 to that shown in FIG. 6. As it begins to move, the hook 143 will catch the vertical run of twine 5 and will put it underneath the underside of the bundle so that it lies substantially above the horizontal leading length of twine 6. Before the knotter 57 arrives at its forward position, the draw slide hook 143 will have moved beyond the path of movement of the knotter, as can be seen in FIG. 6. As the knotter carriage begins to move forward, so the circular profiled cam 72 on the carriage 51 will engage the underside of the arm 119 carrying the trough 121, causing the arm 119 to be lifted and the trough 121 to engage with the length of twine 6 leading back from the button 4 on the chain 1 so as to cause it to lie alongside the length of twine 5.

At the same time, the circular cams 95 will strike the inner sides of the stripper arms 101, 103 causing them to be moved outwardly out of the path of movement of the knotter head,

the heads 111, 113 being their maximum distance apart when the carriage reaches it fully forward position, as can be seen in FIG. 7. As the knotter proceeds to its forward operative position, the two side-by-side lengths of twine will be engaged and held in the slots 93 in the arms 87 and 89 (it will be noticed that two extending arms 155 and 156 are provided on the subframe 131 to ensure this engagement). It will also be noticed that both runs of twine 5 and 6 pass underneath the draw hook 143 and that when the carriage is in its forward operative position, the trough 121 is in alignment with, slightly above, and very close to the draw slide hook 145, thus in efiect forming a nip for two thicknesses of twine. Once the knotter carriage and associated mechanism has reached the position shown in FIG. 6, the gear segment 73 is resented to the knotter gear 69. Initially, the inclined leading surface 74 contacts the underside of the detent 76 and as the cam continues to rotate, so it causes the spring loaded detent locking the knotter against rotation to be moved upwardly out of engagement with the gear 69 so that the knotter is no longer restricted from rotation. The large gear tooth 75 will then engage in the corresponding root in the gear wheel 69, and the knotter will be caused to rotate as the gear segment moves from the position shown in FIG. 6 to the position shown in FIG. 8.

As the knotter begins to rotate so the jaws 61, 63 will engage with the two lengths of twine passing through the nip between the draw slide hook 143 and the lifter arm trough 121 and both runs of the twine will begin to be formed into a loop round both jaws. By the time the knotter has rotated through approximately 180 and reached the position shown in FIG. 8, there will be a loop of two thicknesses of twine around the knotter jaws. As the knotter is further rotated by the gear segment 73, so the cam follower roller 65 will engage the cam 83 which will cause the lower jaw to open, and as rotation of the knotter continues, so the two runs of twine leading back to the slots 93 in the arms 87, 89 will pass between the jaws. Once the knotter has rotated through approximately 270, the cam follower roller 65 will then strike the cam 85 which will cause the lower jaw to close. The knotter will now have rotated through 360 and the. spring loaded detent 76 will run off the inclined trailing end 74 of the segment 73 thereby to engage in the oversized root once again to lock the knotter against further rotation.

The formation of the loop around the knotter jaws tends to tighten the twine around the bundle, as the lengths of twine leading to the slots 93 are firmly held. During the rotation of the knotter, the draw slide arm will move back to the position shown in FIG. 4.

It only remains now for the loop of twine around the jaws to be stripped from the jaws and pulled over the two runs of twine leading back to the slots 93, and a knot will have been formed. In the stripping operation, the knotter carriage and associated mechanism will be moved from its forward operative position to its rear inoperative position during the last 90 of rotation of the cams and as the knotter begins to move rearwards, so the stripper arms will be able to move inwardly and their heads 111, 113 move into engagement with the sides of the jaws of the knotter, and behind the double loop of twine around the jaws. As the carriage and knotter continues rearwards, the stripper heads 111, 113 cause the double loop to be stripped off the jaws and hence around the runs of twine lead ing back to the slots 93, and hence the knot is formed. A

. knotting operation very similar to that described is described and shown in the specification of British Pat. No. 939,259, dated Oct. 9, I963 continues to move rearwards, the twine lifter arm 119 will come off the cam 72 and drop. The length of twine leading back to the slots 93 will still be gripped firmly therein as the arms 87, 89 move rearwardly, and hence, the twine is brought into contact with the knife 123 and thus severed, or is severed by the modified knife mechanism, as has previously been described. As the carriage 51 reaches it rear ward, inoperative position, the abutment 118 is struck by the arm 81 of the knotter jaw release plate 77, and the jaws can then open and release the knotted twine. The next cycle can then be begun.

What we claim is:

1. A knotter mechanism suitable for use in a bundle tying machine, including a frame, a knotter carriage, means mounting said knotter carriage for sliding movement relative to said frame between a forward operative position and a rearward inoperative position, a knotter, means mounting said knotter on said carriage for rotation relative thereto, a cam plate, means mounting said cam plate for rotation relative to the said frame, a cam track on said cam plate, a cam follower carried by said carriage and engaging in said cam track, whereby rotation of said cam plate will cause said sliding movement of the carriage between its operative and inoperative positions, and means to rotate said knotter when said carriage is in its forward operative position.

2. A knotter mechanism according to claim 1, including a shaft rotatably mounted in and passing through the carriage and mounting said knotter on said carriage, and in which said cam follower is mounted on the end of said shaft.

3. A knotter mechanism according to claim 2, including a gear segment, means mounting said segment on the cam plate, a gear wheel provided on the shaft intermediate said knotter and said cam follower, the arrangement being such that when the carriage is in its forward operative position, said gear segment is presented for engagement with said gear wheel to cause rotation of said shaft and hence of said knotter.

4. A knotter mechanism according to claim 3, wherein a spring-loaded detent is mounted on the carriage and is arranged normally to engage with the gear wheel to prevent rotation thereof.

5. A knotter mechanism according to claim 4, wherein the detent is arranged to be released from engagement with said gear wheel when the segment is presented for engagement with said detent. v

6. A knotter mechanism according to claim 1 and including a draw slide cam plate mounted in back-to-back relationship with said cam plate so as to rotate with said cam plate.

7. A knotter mechanism according to claim 1 and including a draw slide control arm, means connecting said control arm at one end to a draw slide mechanism and means pivoting said control arm at its other end to said frame.

8. A knotter mechanism according to claim 7, and including a cam follower provided on the control arm intermediate the ends thereof and a cam track on the draw slide cam plate, in which said cam follower is arranged to engage, the shape of said cam track on the draw slide cam plate being such as to cause reciprocal movement of said draw slide upon rotation of said cam plate.

9. A knotter mechanism according to claim 8, wherein the cam tracks in the two cam plates are so arranged that said draw slide will move from one side of said knotter to the other prior to the knotter reaching its forward operative position,

and once the knotter has begun to rotate and has rotated through approximately the draw slide will move back across the knotter to its original position.

10. A knotter mechanism according to claim 1 and including a twine lifter arm pivotally connected to the frame and further including a cam on the carriage, whereby, upon the carriage beginning its forward movement, the cam engages under the twine lifter arm and lifts it to bring a length of twine into a correct position for engagement by said knotter.

11. A knotter mechanism according to claim 1 wherein the knotter comprises a fixed upper jaw and a pivoted lower jaw and further including a bellcrank for locking said jaws during movement of said carriage, whereby the free end of one of the arms of said bellcrank is arranged to lock said lower jaw and is releasable only when the carriage returns to its rearward position, thereby causing the other arm of said bellcrank to control an abutment to pivot the bellcrank and release the jaw.

12. A knotter mechanism according to claim 1 and including a knife to sever, from a supply of twine, a length of twine positioned and knotted around a bundle. 

1. A knotter mechanism suitable for use in a bundle tying machine, including a frame, a knotter carriage, means mounting said knotter carriage for sliding movement relative to said frame between a forward operative position and a rearward inoperative position, a knotter, means mounting said knotter on said carriage for rotation relative thereto, a cam plate, means mounting said cam plate for rotation relative to the said frame, a cam track on said cam plate, a cam follower carried by said carriage and engaging in said cam track, whereby rotation of said cam plate will cause said sliding movement of the carriage between its operative and inoperative positions, and means to rotate said knotter when said carriage is in its forward operative position.
 2. A knotter mechanism according to claim 1, including a shaft rotatably mounted in and passing through the carriage and mounting said knotter on said carriage, and in which said cam follower is mounted on the end of said shaft.
 3. A knotter mechanism according to claim 2, including a gear segment, means mounting said segment on the cam plate, a gear wheel provided on the shaft intermediate said knotter and said cam follower, the arrangement being such that when the carriage is in its forward operative position, said gear segment is preSented for engagement with said gear wheel to cause rotation of said shaft and hence of said knotter.
 4. A knotter mechanism according to claim 3, wherein a spring-loaded detent is mounted on the carriage and is arranged normally to engage with the gear wheel to prevent rotation thereof.
 5. A knotter mechanism according to claim 4, wherein the detent is arranged to be released from engagement with said gear wheel when the segment is presented for engagement with said detent.
 6. A knotter mechanism according to claim 1 and including a draw slide cam plate mounted in back-to-back relationship with said cam plate so as to rotate with said cam plate.
 7. A knotter mechanism according to claim 1 and including a draw slide control arm, means connecting said control arm at one end to a draw slide mechanism and means pivoting said control arm at its other end to said frame.
 8. A knotter mechanism according to claim 7, and including a cam follower provided on the control arm intermediate the ends thereof and a cam track on the draw slide cam plate, in which said cam follower is arranged to engage, the shape of said cam track on the draw slide cam plate being such as to cause reciprocal movement of said draw slide upon rotation of said cam plate.
 9. A knotter mechanism according to claim 8, wherein the cam tracks in the two cam plates are so arranged that said draw slide will move from one side of said knotter to the other prior to the knotter reaching its forward operative position, and once the knotter has begun to rotate and has rotated through approximately 180*, the draw slide will move back across the knotter to its original position.
 10. A knotter mechanism according to claim 1 and including a twine lifter arm pivotally connected to the frame and further including a cam on the carriage, whereby, upon the carriage beginning its forward movement, the cam engages under the twine lifter arm and lifts it to bring a length of twine into a correct position for engagement by said knotter.
 11. A knotter mechanism according to claim 1 wherein the knotter comprises a fixed upper jaw and a pivoted lower jaw and further including a bellcrank for locking said jaws during movement of said carriage, whereby the free end of one of the arms of said bellcrank is arranged to lock said lower jaw and is releasable only when the carriage returns to its rearward position, thereby causing the other arm of said bellcrank to control an abutment to pivot the bellcrank and release the jaw.
 12. A knotter mechanism according to claim 1 and including a knife to sever, from a supply of twine, a length of twine positioned and knotted around a bundle. 